Priority schemes exist that assign precedence levels to particular calls and other communications sent over a communication network, allowing certain high-priority calls to preempt others in order to ensure bandwidth and clear communication lines for important types or sources of information. Multilevel Precedence and Preemption (MLPP) is one priority scheme that has been used to assign one of several precedence levels to a given communication or call. Calls with a higher precedence level can preempt others with lower precedence levels. Such priority schemes are often used within military and government communications, for instance, to allow high-ranking officials to preempt other lower-level communications so that especially important or urgent messages can be delivered to other officials. For example, the AUTOVON military phone system was equipped with call precedence processing allowing calls of increasing precedence to knock down, or preempt, calls of lower priority.
Like reference numbers and designations in the various drawings indicate like elements.